This invention relates generally to dispensers suitable for delivering an ingredient, such as detergent, to a machine, such as a warewashing machine, and, more particularly to such dispensers responsive to a parameter of the machine, such as the concentration of the ingredient in the machine.
The use of dispensers to dispense a product, or an ingredient, to a machine utilizing the ingredient is well known in the art. Such dispensers may be used for many purposes, one of which is to provide detergent and/or bleach for washing operations.
The amount of ingredient dispensed or delivered to the machine can be a function of the amount of time that the dispenser is active. The longer time, or more time, that the dispenser is active, the more of the ingredient which is dispensed to the machine. Conversely, if the dispenser is active for a shorter time, or for less time, then less of the ingredient is dispensed to the machine.
Further, some controllers dispense the ingredient as a function of a parameter of the machine into which the ingredient is dispensed. In some cases, the ingredient is utilized in the machine in diluted form. As the active ingredient in the working solution of the machine is depleted through machine use, additional ingredient is then dispensed to the machine.
The depletion of the active ingredient can be based upon many factors, such as use of the machine, e.g., the volume of items processed by the machine, temperature and the characteristics of the diluent.
As the concentration level of the active ingredient in the working solution in the machine decreases, the controller can add an additional amount of the active ingredient to replenish the working solution. When the concentration falls too low, the dispenser can be activated until the concentration of the active ingredient returns to acceptable levels or to within the proper range.
One example of an ingredient dispenser is a detergent dispenser for a warewashing machine. A warewashing machine, in a commercial environment, can continuously process trays of dishes as such trays pass through the machine. Detergent is dispensed for optimum concentration of detergent in the detergent/water working solution in the machine. As trays of dishes pass through the warewashing machine, the effectiveness, i.e., the concentration of the detergent, of the working solution decreases.
The concentration of the working solution in the warewashing is monitored, typically by measuring conductivity, possibly in conjunction with temperature. Knowledge of the conductivity and the temperature of the working solution can help to determine the actual concentration of the detergent in the working solution.
However, a malfunction of the detergent dispensing system can lead to disappointing results. A malfunction can lead to too much detergent being dispensed. The dispensing of too much detergent incurs an extra cost of the wasted detergent. Too rich of a detergent solution can also pose increased environmental concerns. A malfunction can also result in ineffective operation of the machine. Not enough detergent can result in improper washing of dishes, possibly requiring the rewashing of the dishes causing a loss in time and expense.
There is a need for an ingredient (or detergent) controller which can detect a malfunction in the ingredient (detergent) replenishment system in order to prevent waste of the active ingredient (detergent) and to prevent improper operation of the machine due to an improper amount of the ingredient being dispensed to the machine.
In one embodiment, the present invention provides a dispenser for dispensing an ingredient for a machine. An ingredient feed mechanism is operatively coupled to dispense the ingredient to the machine and adapted to receive the ingredient. A controller is capable of controlling an amount of the ingredient delivered to the machine by varying an amount of time the ingredient feed mechanism is active. The controller has a demand mode which varies the amount of time the ingredient feed mechanism is active as a function of a parameter obtained from the machine. The controller compares the amount of time the ingredient feed mechanism is active with a reference value. The controller switches to a timed mode if the amount of time deviates from the reference value beyond a first predetermined deviation and which delivers the ingredient as a function of time.
In another embodiment, the present invention is a dispenser for dispensing a detergent for a warewashing machine. A detergent feed mechanism is operatively coupled to dispense the detergent to the warewashing machine and adapted to receive the detergent. A controller is capable of controlling an amount of the detergent delivered to the warewashing machine by varying an amount of time the detergent feed mechanism is active. The controller has a demand mode which varies the amount of time the detergent feed mechanism is active as a function of a concentration of the detergent in the warewashing machine. The controller compares the amount of time the detergent feed mechanism is active with a reference value. The controller switches to a timed mode if the amount of time deviates from the reference value beyond a first predetermined deviation and which delivers the detergent as a function of time.
In a preferred embodiment, the controller has an initial training mode which measures the amount of time the ingredient feed mechanism is active over a predetermined period of time while delivering the ingredient in accordance with the parameter and establishes the reference value based upon the amount of time the ingredient feed mechanism is active.
In a preferred embodiment, the controller switches back to the demand mode if the amount of time returns to within a second predetermined deviation from the reference value.
In a preferred embodiment, the first predetermined deviation is a result of the amount of time exceeding the reference value.
In a preferred embodiment, the amount of time is determined by a moving average.
In a preferred embodiment, the moving average is determined by an FIR filter having a time constant of at least one hour.
In a preferred embodiment, the parameter is a concentration value of the ingredient in the machine.
In a preferred embodiment, the controller in the timed mode delivers the ingredient solely as a function of time.
In another embodiment, the present invention is a method of dispensing ingredient for a machine, the machine have a ingredient feed mechanism operatively coupled to dispense the ingredient to the machine and adapted to receive the ingredient; and a controller capable of controlling an amount of the ingredient delivered to the machine by varying an amount of time the ingredient feed mechanism is active. In a demand mode, the amount of time the feed mechanism is active is varied as a function of a concentration of the ingredient in the machine. The amount of time the ingredient feed mechanism is active is compared with a reference value. The controller switches to a timed mode in which the ingredient is delivered as a function of time if the amount of time deviates from the reference value beyond a first predetermined deviation.
In another embodiment, the present invention provides a method of dispensing detergent for a warewashing machine, the warewashing machine have a detergent feed mechanism operatively coupled to dispense the detergent to the warewashing machine and adapted to receive the detergent; and a controller capable of controlling an amount of the detergent delivered to the warewashing machine by varying an amount of time the detergent feed mechanism is active. In a demand mode, the amount of time the detergent feed mechanism is active is varied as a function of a concentration of the detergent in the warewashing machine. The amount of time the detergent feed mechanism is active is compared with a reference value. The controller switches to a timed mode in which the detergent is delivered as a function of time if the amount of time deviates from the reference value beyond a first predetermined deviation.
In a preferred embodiment, the method first, in a training mode, measures the amount of time the ingredient feed mechanism is active over a predetermined period of time while delivering the ingredient in accordance with the parameter and establishes the reference value based upon the amount of time the ingredient feed mechanism is active.
In a preferred embodiment, the method switches back to the demand mode if the amount of time returns to within a second predetermined deviation from the reference value.
In a preferred embodiment, the first predetermined deviation is a result of the amount of time exceeding the reference value.
In a preferred embodiment, the amount of time is determined by a moving average.
In a preferred embodiment, the moving average is determined by an FIR filter having a time constant of at least one hour.
In a preferred embodiment, the method, in the timed mode, delivers the ingredient solely as a function of time.